The invention relates to novel hindered amine derivatives containing 0-acyl, 0-carbamoyl or 0-carbonate groups on the hindered nitrogen atom of the nitrogen-containing heterocyclic ring and a diversity of substituents on the 4-position of the ring.
Various N-acyloxy and N-carbamoyloxy hindered amine derivatives have been disclosed. N-Acetoxy and N-benzoyloxy derivatives prepared from the N-hydroxy starting material are described in Kurumada et al, J. Polym. Sci, Polym. Chem. Ed. 22, 277-81 (1984). Felder et al., Helv. Chim. Acta. 63, 132 (1980) teach the preparation of an N-phenylacetoxy derivative. N-(Phenylcarbamoyl)oxy derivatives of N-hydroxy hindered amines have been reported in Rozantsev et al, Isv. Akad. Nauk SSSR, Ser. Khim. 5, 891-6 (1966). The bis(N-acetoxypiperidyl) sebacate has been disclosed in Carlsson et al, Polym. Science Technol. 26, 35-47 (1984). Finally, U.S. Pat. No. 4,472,547 discloses various N-piperidyl lactam compounds such as an N-benzoyloxy hindered amine containing a 4-(2-oxohexamethyleneimine) substituent as light stabilizers for polyolefins and other organic polymers.
The instant invention relates to hydroxylamine derivatives having one of formulae A to P ##STR1## wherein R is hydrogen or methyl,
R.sub.1 is ##STR2## wherein D is C.sub.1 -C.sub.18 alkyl, C.sub.1 -C.sub.18 alkoxy, phenyl, phenyl substituted by hydroxy, alkyl or alkoxy, or amino or amino mono- or disubstituted by alkyl or phenyl; PA1 m is 1-4, PA1 when m is 1, PA1 R.sub.2 is ##STR3## wherein x is 0 or 1, or ##STR4## wherein y is 2-4; when m is 2 and D is alkyl, phenyl or substituted phenyl, PA1 R.sub.2 is C.sub.1 -C.sub.12 alkylene, C.sub.4 -C.sub.12 alkenylene, xylylene, a divalent acyl radical of a cycloaliphatic, araliphatic or aromatic dicarboxylic acid or of a dicarbamic acid, preferably an acyl radical of a cycloaliphatic or aromatic dicarboxylic acid having 8-14 C atoms, or of an aliphatic, cycloaliphatic or aromatic dicarbamic acid having 8-14 atoms; ##STR5## wherein D.sub.1 is an aryl or aralkyl radical including 3,5-di-t-butyl-4-hydroxybenzyl radical, D.sub.2 is D.sub.1 or hydrogen, D3 is an alkenyl radical containing up to 18 carbon atoms, and d is 0-20; PA1 when m is 2 and D is amino, substituted amino or alkoxy, PA1 R.sub.2 is C.sub.1 -C.sub.12 alkylene, C.sub.4 -C.sub.12 alkenylene, xylylene, a divalent acyl radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, or of a dicarbamic acid; preferably an acyl radical of an aliphatic dicarboxylic acid having 2-18 C atoms, of a cycloaliphatic or aromatic dicarboxylic acid having 8-14 C. atoms, or of an aliphatic, cycloaliphatic or aromatic dicarbamic acid having 8-14 C atoms; ##STR6## wherein D.sub.4 and D.sub.5 are independently hydrogen, an alkyl radical containing up to 8 carbon atoms, an aryl or aralkyl radical including 3,5-di-t-butyl-4-hydroxybenzyl radical, D.sub.6 is hydrogen, or an alkyl or alkenyl radical containing up to 18 carbon atoms, and d is 0-20; PA1 p is 1, 2 or 3, PA1 R.sub.3 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.7 -C.sub.9 aralkyl, C.sub.2 -C.sub.18 alkanoyl, C.sub.3 -C.sub.5 alkenoyl or benzoyl; PA1 when p is 1, PA1 R.sub.4 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 -C.sub.8 alkenyl unsubstituted or substituted by a cyano, carbonyl or carbamide group, aryl, aralkyl, or it is glycidyl, a group of the formula --CH.sub.2 --CH(OH)--Z or of the formula --CO--Z-- or --CONH--Z wherein Z is hydrogen, methyl or phenyl; or a group of the formulae ##STR7## when p is 2, R.sub.4 is C.sub.1 -C.sub.12 alkylene, C.sub.6 -C.sub.12 arylene, xylylene, a --CH.sub.2 CH(OH)--CH.sub.2 group, or a group --CH.sub.2 --CH(OH)--CH.sub.2 --O--X--O--CH.sub.2 --CH(OH)--CH.sub.2 -- wherein X is C.sub.2 --C.sub.10 alkylene, C.sub.6 --C.sub.15 arylene or C.sub.6 --C.sub.12 cycloalkylene; or, provided that R.sub.3 is not alkanoyl, alkenoyl or benzoyl, R.sub.4 can also be a divalent acyl radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or dicarbamic acid, or can be the group --CO--; or R.sub.3 and R.sub.4 together when p is 1 can be alkylene of 4 to 6 carbon atoms or 2-oxo polyalkylene or the cyclic acyl radical of an aliphatic or aromatic 1,2- or 1,3-dicarboxylic acid, or ##STR8## where T.sub.8 and T.sub.9 are independently hydrogen, alkyl of 1 to 18 carbon atoms, or T.sub.8 and T.sub.9 together are alkylene of 4 to 6 carbon atoms or 3-oxapentamethylene, preferably T.sub.8 and T.sub.9 together are 3-oxapentamethylene; PA1 when p is 3, PA1 R.sub.4 is 2,4,6-triazinyl, PA1 when n is 1, PA1 R.sub.5 and R'.sub.5 are independently C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.12 alkenyl, C.sub.7 -C.sub.12 aralkyl, or R.sub.5 is also hydrogen, or R.sub.5 and R'.sub.5 together are C.sub.2 -C.sub.8 alkylene or hydroxyalkylene or C.sub.4 -C.sub.22 acyloxyalkylene; PA1 when n is 2, PA1 R.sub.5 and R'.sub.5 together are (--CH.sub.2).sub.2 C(CH.sub.2 --).sub.2 ; PA1 R.sub.6 is hydrogen, C.sub.1 -C.sub.12 alkyl, allyl, benzyl, qlycidyl or C.sub.2 -C.sub.6 alkoxyalkyl; PA1 when n is 1, PA1 R.sub.7 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.3 -C.sub.5 alkenyl, C.sub.7 -C.sub.9 aralkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 -C.sub.4 hydroxyalkyl, C.sub.2 -C.sub.6 alkoxyalkyl, C.sub.6 -C.sub.10 aryl, glycidyl, a group of the formula --(CH.sub.2).sub.m --COO--Q or of the formula --(CH.sub.2).sub.m --O--CO--Q wherein m is 1 or 2, and Q is C.sub.1 -C.sub.4 alkyl or phenyl; or PA1 when n is 2, PA1 R.sub.7 is C.sub.2 -C.sub.12 alkylene, C.sub.6 -C.sub.12 arylene, a group --CH.sub.2 CH(OH)--CH.sub.2 --O--X--O--CH.sub.2 --CH(OH)--CH.sub.2 -- wherein X is C.sub.2 -C.sub.10 alkylene, C.sub.6 -C.sub.15 arylene or C.sub.6 -C.sub.12 cycloalkylene, or a group --CH.sub.2 CH(OZ')CH.sub.2 --(OCH.sub.2 --CH(OZ')CH.sub.2).sub.2 -- wherein Z' is hydrogen, C.sub.1 -C.sub.18 alkyl, allyl, benzyl, C.sub.2 -C.sub.12 alkanoyl or benzoyl; PA1 Q.sub.2 is --N(R.sub.8)-- or --O--; E is C.sub.1 --C.sub.3 alkylene, the group --CH.sub.2 --CH(R.sub.9)--O-- wherein R.sub.9 is hydrogen, methyl or phenyl, the group --(CH.sub.2).sub.3 --NH-- or a direct bond; PA1 T.sub.4 has the same meaning as R.sub.4 when p is 1 or 2, PA1 T.sub.5 is methyl, PA1 T.sub.6 is methyl or ethyl, or T.sub.5 and T.sub.6 together are tetramethylene or pentamethylene or mixture of said hydroxylamine derivatives, preferably T.sub.5 and T.sub.6 are each methyl, PA1 M and Y are independently methylene or carbonyl preferably M is methylene and Y is carbonyl, and T.sub.4 is ethylene where n is 2; PA1 T.sub.7 is the same as R.sub.7, and T.sub.7 is preferably octamethylene when n is 2, PA1 T.sub.10 and T.sub.11 are independently alkylene of 2 to 12 carbon atoms, or T.sub.11 is ##STR11## T.sub.12 is ##STR12## where R.sub.11 is the same as R.sub.3 or is also ##STR13## a, b and c are independently 2 or 3, and f is 0 or 1, preferably a and c are each 3, b is 2 and f is 1; and PA1 e is 3 or 4, preferably 4; PA1 T.sub.13 is the same as R4 with the proviso that T.sub.13 cannot be hydrogen when p is 1; PA1 E.sub.1 and E.sub.2 m being different, each are --CO-- or --N(E.sub.5)-- where E.sub.5 is hydrogen, C.sub.1 -C.sub.12 alkyl or C.sub.4 -C.sub.22 alkoxycarbonylalkyl, preferably E.sub.1 is --CO-- and E.sub.2 is --N(E.sub.5)--, PA1 E.sub.3 is hydrogen, alkyl of 1 to 30 carbon atoms, phenyl, naphthyl, said phenyl or said naphthyl substituted by chlorine or by alkyl of 1 to 4 carbon atoms, or phenylalkyl of 7 to 12 carbon atoms, or said phenylalkyl substituted by alkyl of 1 to 4 carbon atoms, PA1 E.sub.4 is hydrogen, alkyl of 1 to 30 carbon atoms, phenyl, naphthyl or phenylalkyl of 7 to 12 carbon atoms, or PA1 E.sub.3 and E.sub.4 together are polymethylene of 4 to 17 carbon atoms, or said polymethylene substituted by up to four alkyl groups of 1 to 4 carbon atoms, preferably methyl, and
when m is 3, R.sub.2 is a trivalent acyl radical of an aliphatic, unsaturated aliphatic, cycloaliphatic, or aromatic tricarboxylic acid;
when m is 4, R.sub.2 is a tetravalent acyl radical of a saturated or unsaturated aliphatic or aromatic tetracarboxylic acid including 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-but-2-enetetracarboxylic acid, and 1,2,3,5- and 1,2,4,5-pentanetetracarboxylic acid;
R.sub.10 is hydrogen or C.sub.1 -C.sub.18 alkyl, R.sub.8 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.7 -C.sub.12 aralkyl, cyanoethyl, C.sub.6 -C.sub.10 aryl, the group --CH.sub.2 --CH(R.sub.9)--OH wherein R.sub.9 has the meaning defined above; a group of the formula ##STR9## or a group of the formula ##STR10## wherein G can be C.sub.2 -C.sub.6 alkylene or C.sub.6 -C.sub.12 arylene; or R.sub.8 is a group --E--CO--NH--CH.sub.2 --OR.sub.10 ;
Formula F denotes a recurring structural unit of a polymer where T.sub.3 is ethylene or 1,2-propylene, or is the repeating structural unit derived from an alpha-olefin copolymer with an alkyl acrylate or methacrylate; preferably a copolymer of ethylene and ethyl acrylate, and where k is 2 to 100;
R.sub.2 of formula (N) is as previously defined when m is 1, and G.sub.2 is a direct bond, C.sub.1 -C.sub.12 alkylene, phenylene or --NH--G'--NH wherein G' is C.sub.1 -C.sub.12 alkylene.
In the structures A to N, if any substituents are C.sub.1 -C.sub.18 alkyl, they are for example methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl. Typical cycloalkyl groups include cyclopentyl and cyclohexyl, while typical aralkyl groups include benzyl, alpha-methyl-benzyl, alpha,alpha-dimethylbenzyl or phenethyl.
If R.sub.2 is a divalent acyl radical of a dicarboxylic acid, it is for example an acyl radical of adipic acid, succinic acid, suberic acid, sebacic acid, phthalic acid, dibutylmalonic acid, dibenzylmalonic acid or (3,5-di-tert-butyl-4-hydroxybenzyl)-malonic acid, or bicycloheptenedicarboxylic acid.
If R.sub.2 is a divalent acyl radical of a dicarbamic acid, it is for example an acyl radical of hexamethylenedicarbamic acid or of 2,4-toluylenedicarbamic acid.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula A. (Depending on the selected preparative procedure).
di-(2,2,6,6-tetramethylpiperidin-4-yl)phthalate alpha,alpha'-(di-2,2,6,6-tetramethylpiperidine-4-oxy)-p-xylene PA0 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine 1-acetoxy-4-hydroxy-2,2,6,6-tetramethylpiperidine di-(1-oxyl-2,2,6,6-tetramethylpiperdin-4-yl) phthalate PA0 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one (1-hydroxy-2,2,6,6-tetramehylpiperdin-4-yl) stearate (2,2,6,6-tetramethylpiperidin-4-yl)-[4-(2-oxoazepin-1-yl)-2,2,6,6-tetramet hylpiperidin-4-yl]acetate PA0 N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diamine, PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diacetamide, PA0 4-benzylamino-2,2,6,6-tetramethylpiperidine, PA0 N-n-butyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)-4-hydroxy-3,5-di-tert.butyl benzamide, PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-di-butyl-adipamide, PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dicyclohexyl-(2-hydroxypr opylene-diamine), PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-p-xylylenediamine, PA0 4-(3-methyl-4-hydroxy-5-tert-butyl-benzoyl acetamido)-2,2,6,6-tetramethylpiperidine, PA0 alpha-cyano-.beta.-methyl-.beta.-[N-(2,2,6,6-tetramethylpiperidin-4-yl]-ami no-acrylic acid methyl ester, PA0 1-acetoxy-4-butylamino-2,2,6,6-tetramethyl piperidine PA0 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one. PA0 9-aza-8,8,10,10-tetramethyl-1,5-dioxaspiro[5.5]undecane, PA0 9-aza-8,8,10,10-tetramethyl-3-ethyl-1,5-dioxaspiro[5.5]undecane, PA0 2,2,6,6-tetramethylpiperidine-4-spiro-2'-(1',3'-dioxane)5'-spiro-5"-(1",3"- dioxane)-2"-spiro-4"'-(2"',2"'-6"',6"'-tetramethylpiperidine). PA0 3-benzyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]-decane-2,4-dione, PA0 3-n-octyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]-decane-2,4-dione, PA0 3-allyl-1,3,8-triaza-1,7,7,9,9-pentamethylspiro[4.5]-decane-2,4-dione, or the compounds of the following formulae: ##STR14## As C.sub.5 -C.sub.7 cycloalkyl, R.sub.8 is in particular cyclohexyl. PA0 N-hydroxymethyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea, PA0 N-methoxymethyl-N'-2,2,6,6-tetramethylpiperidin-4-yl urea, PA0 N-methoxymethyl-N'-n-dodecyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea, and PA0 O-(2,2,6,6-tetramethylpiperidin-4-yl)-N-methoxymethylurethane. PA0 poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(1-o xyl-2,2,6,6-tetramethylpiperidyl)-imino]-hexamethylene-4[4-(1-oxyl-2,2,6,6- tetramethylpiperidyl]-imino}, PA0 2,3,9,10-perylene tetracarboxylic acid dianhydride PA0 1,4,5,8-naphthalene tetracarboxylic acid dianhydride PA0 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride PA0 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride PA0 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride PA0 phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride 2,3,3',4'-benzophenonetetracarboxylic acid dianhydride pyromellitic dianhydride PA0 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride PA0 2,2',3,3'-benzophenonetetracarboxylic acid dianhydride PA0 3,3',4,4'-biphenyltetracarboxylic acid dianhydride PA0 2,2',3,3'-biphenyltetracarboxylic acid dianhydride PA0 4,4'-isopropylidenediphthalic anhydride PA0 3,3'-isopropylidenediphthalic anhydride PA0 4,4'-oxydiphthalic anhydride PA0 4,4'-sulfonyldiphthalic anhydride PA0 3,3'-oxydiphthalic anhydride PA0 4,4'-methylenediphthalic anhydride PA0 4,4'-thiodiphthalic anhydride PA0 4,4'-ethylidenediphthalic anhydride PA0 2,3,6,7-naphthalenetetracarboxylic acid dianhydride PA0 1,2,4,5-naphthalenetetracarboxylic acid dianhydride PA0 1,2,5,6-naphthalenetetracarboxylic acid dianhydride benzene-1,2,3,4-tetracarboxylic acid dianhydride pyrazine-2,3,5,6-tetracarboxylic acid dianhydride.
As C.sub.2 -C.sub.18 alkanoyl, R.sub.3 is for example propionyl, butyryl, octanoyl, dodecanoyl, hexadecanoyl, octadecanoyl, but preferably acetyl; and as C.sub.3 -C.sub.5 alkenoyl, R.sub.3 is in particular acryloyl.
If R.sub.4 is C.sub.2 -C.sub.8 alkenyl unsubstituted or substituted by a cyano, carbonyl or carbamide group, it is for example 1-propenyl, allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl, 2,2-dicyanovinyl, 1-methyl-2-cyano-2-methoxycarbonyl-vinyl or 2,2-diacetylaminovinyl.
If any substituents are C.sub.2 -C.sub.12 alkylene, they are for example ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.
If any substituents are C.sub.6 -C.sub.15 arylene, they are for example o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.
As C.sub.6 -C.sub.12 cycloalkylene, X is especially cyclohexylene.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula B.
If R5 is C.sub.2 -C.sub.8 alkylene or hydroxyalkylene, it is for example ethylene, 1-methyl-ethylene, propylene, 2-ethylpropylene or 2-ethyl-2-hydroxymethylpropylene.
As C.sub.4 -C.sub.22 acyloxyalkylene, R.sub.5 is for example 2-ethyl-2-acetoxymethyl-propylene.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula C.
If any substituents are C.sub.2 -C.sub.6 alkoxyalkyl, they are for example methoxymethyl, ethoxymethyl, propoxymethyl, tert-butoxyethyl, ethoxyethyl, ethoxypropyl, n-butoxyethyl, tert-butoxyethyl, isopropoxyethyl or propoxypropyl.
If R.sub.7 is C.sub.3 -C.sub.5 alkenyl, it is for example 1-propenyl, allyl, methallyl, 2-butenyl or 2-pentenyl.
As C.sub.7 -C.sub.9 aralkyl, R.sub.7 is in particular phenethyl or above all benzyl; and as C.sub.5 -C.sub.7 cycloalkyl, R.sub.7 is especially cyclohexyl.
If R.sub.7 is C.sub.2 -C.sub.4 hydroxyalkyl, it is for example 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.
As C.sub.6 -C.sub.10 aryl, the substituents are in particular phenyl, or alpha- or .beta.-naphthyl which is unsubstituted or substituted by halogen or C.sub.1 -C.sub.4 alkyl.
If R.sub.7 is C.sub.2 -C.sub.12 alkylene, it is for example ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.
If R.sub.7 is C.sub.6 -C.sub.12 arylene, it is for example o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.
If Z' is C.sub.2 -C.sub.12 alkanoyl, it is for example propionyl, butyryl, octanoyl, dodecanoyl or preferably acetyl.
The following compounds are examples of polyalkylpiperidine starting materials useful in making hydroxylamine derivatives of formula D.
As C.sub.6 -C.sub.10 aryl, R.sub.8 is particularly phenyl, or alpha- or .beta.-naphthyl which is unsubstituted or substituted with halogen or C.sub.1 -C.sub.4 alkyl.
As C.sub.1 -C.sub.3 alkylene, E is for example methylene, ethylene or propylene.
As C.sub.2 -C.sub.6 alkylene, G is for example ethylene, propylene, 2,2-dimethylpropylene, tetramethylene or hexamethylene; and as C.sub.6 -C.sub.12 arylene, G is o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula E.
When the instant hydroxylamine derivative is of formula F, the following polymeric compounds are examples of starting materials useful in preparing said derivatives. ##STR15##
Additional starting hindered amine derivatives include for formula J:
For compounds of formula O, R.sub.3 is preferably C.sub.1 -C.sub.12 alkyl and C.sub.5 -C.sub.7 cycloalkyl and more preferably methyl, octyl, dodecyl and cyclohexyl.
For compounds of formula P, the following species are typical of tetracarboxylic acid dianhydrides suitable for the preparation thereof:
The hydroxylamine derivatives of the instant invention are generally prepared by oxidizing the corresponding hindered amine with an appropriate peroxy compound such as hydrogen peroxide or tert-butyl hydroperoxide in the presence of a metal carbonyl or metal oxide catalyst followed by reduction of the oxyl intermediate formed to the desired N-hydroxy derivative, preferably by catalytic hydrogenation.
Thereafter, the N-acyloxy, N-carbamoyloxy and N-(alkoxyacyl)oxy derivatives are prepared by reacting the N-hydroxy hindered amine with the appropriate acid chloride, anhydride, cyanate, isocyanate or substituted chloroformate (for carbonates). The catalytic hydrogenation can also be conducted in acetic anhydride to prepare the N-acetoxy derivative.
The oxalates of formula N can be prepared by reacting (1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl)stearate, benzoate, and the like, with oxalyl chloride, or for R.sub.2 being --NH--G'--NH by reacting the appropriate 1-hydroxy-2,2,6,6-tetramethyl piperidine with the appropriate diisocyanate.
These reactions are generally conducted at temperatures ranging from 0 to 60.degree. C. and in a variety of solvents including toluene and dichloromethane. The reactions are also preferably conducted in the presence of an acid acceptor such as triethylamine. The various hindered amine precursors are largely commercially available or can be prepared by methods known in the art.
The derivatives are particularly effective in stabilizing organic materials against the degradative effects of actinic stimuli. Such organic materials include polyolefins, vinyl chloride polymers, elastomers, polyesters and polyurethanes. They are particularly active as light stabilizers in ambient cured and acid catalyzed thermoset coatings or enamels. Since these materials are considerably less basic than conventional hindered amines, they do not inhibit or interfere with cure as is encountered with the conventional hindered amines nor are they interacting. They likewise do not exhibit the color problems encountered with nitroxyl radicals and, unlike N-hydroxy hindered amines, tend to resist air oxidation during handling. Finally, the N-acyloxy hindered amines exhibit greater solubility in the solvents typically utilized in coatings. These areas are further described in U.S. application Ser. Nos. 07/099,411 and 07/099,420 both abandoned.
The following examples will further illustrate the embodiments of this invention.